Liquid propellant weapon

ABSTRACT

A small bore liquid propellant weapon fires projectiles transported to the firing chamber in a projectile carrier. The projectile carrier is separated from the projectile just prior to firing the projectile. The projectile carrier can be reconnected with the projectile to extract the projectile from the weapon in the event of a misfire. The small bore liquid propellant weapon has a reciprocating combustion chamber housing. The reciprocating combustion chamber housing forms a large diameter combustion chamber without ullage and eliminates a lock. The small bore liquid propellant weapon includes an integral magazine which has its own pump for the liquid propellant. The magazine also has a valve element with high pressure seals that operate only for the life of the magazine and that are discarded with the empty magazine.

Elmore et al.

[451 Apr. 16, 1974 Primary Examiner-Samuel W. Engle Attorney, Agent, orFirm-Donald C. Feix ABSTRACT A small bore liquid propellant weapon firesprojectiles transported to the firing chamber in a projectile carrier.The projectile carrier is separated from the projectile just prior tofiring the projectile. The projectile carrier can be reconnected withthe projectile to extract the projectile from the weapon in the event ofa The small bore liquid propellant weapon has a reciprocating combustionchamber housing. The reciprocating combustion chamber housing forms alarge diameter combustion chamber without ullage The small bore liquidpropellant weapon includes an integral magazine which has its own pumpfor the liquid propellant. The magazine also has a valve element withhigh pressure seals that operate only for the life of the magazine andthat are discarded with 19 Claims, 27 Drawing Figures i 1 LIQUIDPROPELLANT WEAPON 175] Inventors: Lester C. Elmore, Portola Valley;Thomas M. Broxholm, Palo Alto, both of Calif. [57] i 73] Assignee:Pulsepower Systems Inc., San

Carlos, Calif.

[22] Filed: Sept. 13, 1971 [2]] Appl. No.: 179,759

52 us. Cl 89/7, 89/194, 102/38 [51] Int. Cl F41f l/04 [58] Field ofSearch..... 89/1, 7, 26, 194; 102/38 {56] References Cited UNITED STATESPATENTS and el'mmates a |.359,295 ll/l920 Trumble 89/7 2,129,875 9/l938Rost 89/7 3.455.202 7/1969 Dixon et al. 89/7 407.474 7/1889 Dudley 89/72.922.341 l/l960 Treat, Jr. 89/7 2,947,221 8/1960 Griffin et al. 89/7the empty magazine 3,0l 1.451 12/1961 Griffin 89/7 X IO Ill 03 e A r I.r n I u /IIO PATENTED APR 1 6 i974 FIG...14

SHEU 10F 7 &

FlGml I NVE N'TORS LESTER C. ELMORE THOMAS M. BROXHOLM TTORNEYSPATENTEDAPR 16 1914 3.803. 975

INVENTORS LESTER C. ELMORE G 7 THOMAS M. BROXHOLM ATTORNEYS PATENTED APR1 6 I974 SHEEI 30? 7 LESTER C. ELMORE THOMAS M. BROXHOLM 1 5 ATTORNEYSmidi 1 v /A r J a m %m t 4 A m i PATENTEUAPR 16 I974 INVENTORS LESTER C.ELMORE THOMAS M. BROXHOLM J J -jiiav'aJgrl ATTORNEYS PATENTEU R 16 '93,803,975

SHEEI 5 0F 7 SOLID PROPELLANT PEAK TEMP. EZZJ souo PROPELLANT u4oc) I000m LIQUID PROPELLANT BORE SURFACE TEMP. (0)

LIQUID PROPELLANT PEAK TEMP.

0 IO 20 3O 4O 5O 6O 70 F BARREL LENGTH INCHES DRAG COEFFICIENT 0 MUZZLEc MUZZLE T D VELOCITY- 3450 20 \y A 3850 FT VELOCITY 4- g. MUZZLE FTVELOCITY'SOOO 4 1 I 2 a 4 5 e 7 MACH NUMBER F INVENTORS LESTER C. ELMORETHOMAS M. BROXHOLM ATTOR EYS PATENTEUAPR 16 mm 3.803; 975

SHEET 7 0F 7 FlG. 23

' I84 FIG 22 FiG. 2IA 53 FiG 2IB 62 FIG 2lD IN VENTOR.

LESTER C. ELMORE J BY THOMAS M. BROXHOLM ATTORNEYS LIQUID PROPELLANTWEAPON BACKGROUND OF THE INVENTION I. Field of the Invention Theinvention relates to a liquid propellant weapon. The invention relatesparticularly to a small bore liquid propellant weapon of the kind thatcan be carried and used by an individual infantryman.

2. Description of the Prior Art Existing weapons for infantrymen usesolid propellant cartridges. The existing weapons carry the solidpropellant in cases, and the cases form a substantial part of theoverall weight of the cartridge. It is characteristic of the solidpropellant that the solid propellant develops a high peak temperature.

The trend in small arms development is towards higher projectilevelocity. Higher projectile velocity has a number of advantages. Highervelocity yields increased projectile kinetic energy and penetratingpower. Smaller projectiles can be used, and the effective range can beincreased.

High velocity, conventional, cased ammunition purchases performance atthe expense of increased propellant charge and a larger cartridge case.

The high peak temperatures of solid propellants also can cause problemsof barrel erosion. This has limited the velocity obtainable with solidpropellants in small bore weapons.

Caseless solid propellant systems have been investigated in an attemptto eliminate the weight of the case. The caseless solid propellantsystems have not avoided the problem of high propellant peaktemperatures which, heating the barrel, limited the projectile velocitythat can be obtained.

Liquid propellant weapons have a characteristic low peak temperature.Substantial investigation has been made of the use of liquid propellantsfor automatic weapons. However, most of the prior liquid propellantweapon work completed to date has involved equipment of a bore-sizelarger than caliber 0.60. Prior work with large bore liquid propellantweapons has been directed to a projectile loading concept based on aboresize chamber in which a caseless projectile is loaded into thebreech and is subsequently pumped into the forcing cone by thepropellant charge which then completely fills the combustion chamber.While facilitating the projectile loading process, this geometry resultsin two problems. It becomes extremely difficult to retrieve theprojectile in the event of a misfire, since no connection is availableto the projectile, nor is there a convenient means of effecting anattachment once the projectile is in place.

An equally important consideration is that of performance limitations.In weapons requiring high muzzle velocity and hence largepropellant-to-projectile mass ratios the length to diameter ratio of thecombustion chamber becomes excessive for acceptable interior ballistics.The bore-size chamber approach, therefore, has been considered to belimited to velocities of approximately 4,000 feet per second or less.

SUMMARY OF THE INVENTION The small bore liquid propellant weapon of thepresent invention has a combustion chamber diameter which is much largerthan the bore of the barrel of the weapon.

minimizes receiver length and improves chamber wall cooling. This alsopermits the use of a stationary lock for the combustion chamber. Itprovides a convenient means of thermal isolation of the combustionchamber and a convenient means of handling a projectile in a gunemploying chambrage. It permits the velocity level to be readilyincreased by using a longer chamber and stroke. It also permits thelength of propellant passages in a receiver mechanism to be limited, andthis in turn simplifies the mechanism, eliminates voids and eliminatespropellant filled passages which could transmit flame from thecombustion chamber to the propellant supply in the magazine.

In the present invention the projectile is carried in a projectilecarrier which is separated from the projectile prior to firing. Theprojectile is a low drag conical projectile. It has the shape of areentry body with a narrow angle cone and is aerodynamically stabilized.

The carrier contains a percussion igniter which allows the use ofexisting ignition techniques applicable to any of the current liquidpropellant systems.

The carrier can be reengaged with the projectile to remove theprojectile in the event of misfire.

The projectile carrier is also a key element in transporting theprojectile through the larger than bore diameter chamber (chambrage)which is necessary in a high performance gun.

The weapon of the present invention includes a magazine which has apumping mechanism integral with the magazine. The pumping mechanism isoperated by the action of the reciprocating bolt of the weapon. Apropellant supply valve and high pressure seals on the valve are anintegral part of the magazine. The incorporation of the high pressureseals as an integral part of the magazine, and the manner in which themagazine and the high pressure valve are associated with the rest of theweapon have several advantages. The high pressure valve element andseals have to operate only for the life of the magazine. The valveelement and seals are discarded with the empty magazine. A new highpressure inlet valve element and new high pressure seals are providedeach time the magazine is replaced.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show preferredembodiments of the present invention and the principles thereof and whatare now considered to be the best modes contemplated for applying theseprinciples. Other embodiments of the invention embodying the same orequivalent principles may be used and structural changes may be made asdesired by those skilled in the art without departing from the presentinvention and the purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of asmall bore liquid propellant weapon constructed in accordance with oneembodiment of the present invention;

FIG. 2 is a side elevation view in cross section of a projectile-carrierassembly constructed in accordance with one embodiment of the presentinvention;

FIG. 3 is an end elevation view taken along the line and in thedirection indicated by the arrows 33 in FIG. 2;

FIG. 4 is a side elevation view of the carrier alone;

FIG. 5 is a side elevation view of the projectile alone;

FIG. 6 is an end elevation view taken along the line and in thedirection indicated by the arrows 6-6 in FIG. 5;

FIG. 7 is a side elevation view (partly broken away to show details ofconstruction) of a magazine constructed in accordance with oneembodiment of the present invention;

FIG. 8 is an end elevation view taken along the line and in thedirection indicated by the arrows 8-8 in FIG. 7;

FIG. 9 is a fragmentary, enlarged, side elevation, cross-sectional viewshowing the magazine loaded in the weapon;

FIG. 10 is a top plan view taken generally along the line and in thedirection indicated by the arrows 10-10 in FIG. 9;

FIGS. 11-15 are schematic side elevation views of the structure shown inFIG. 9 showing the position assumed by the different elements of thestructure during a cycle of automatic firing operation;

FIG. 16 is a graph showing the comparison of temperatures in a barrelfor solid propellants and for liquid propellants;

FIG. 17 is a graph showing the drag coefficient for different types ofprojectiles;

FIG. 18 is a fragmentary side elevation view in crosssection, like FIG.9, of a weapon constructed in accordance with another embodiment of thepresent invention. The embodiment shown in FIG. 18 incorporates areciprocating combustion chamber housing;

FIG. 19 is an end elevation view taken generally along the line and inthe direction indicated by the arrows 19l9 in FIG. 18;

FIG. 20 is a plan view showing the cam paths for actuating the bolt ofthe embodiment shown in FIG. 18;

FIGS. 21 A through D are side elevation views of a carrier incorporatinga positive misfire extraction construction;

FIG. 22 is a side elevation of a magazine constructed in accordance withanother embodiment of the present invention;

FIG. 23 is a fragmentary sectional view taken generally along the lineand in the direction indicated by the arrows 23 23 in FIG. 22; and

FIG. 24 is a detail view of a strap transfer mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT A small bore liquid propellantweapon constructed in accordance with one embodiment of the presentinvention is indicated generally by the reference numeral 41 in FIG. 1.

The weapon 41 is illustrated as a shoulder weapon. The present inventioncould also be embodied in other types of weapons, such as hand weaponsor vehicle mounted weapons.

The principal components of the weapon 41 are a barrel 43, a receiverassembly 45 and a magazine 47.

The receiver assembly will be described with reference to FIGS. 9 and 10for one embodiment of the present invention and with reference to FIGS.18 and 19 with reference to another embodiment of the present invention.

The magazine 47 will be described below with reference to FIGS. 7, 8, 9,18, 22 and 23.

The magazine 47 supplies liquid propellant and projectiles to thereceiver assembly 45 of weapon 41. Each of the projectiles istransported through the magazine and receiver assembly and into thefiring chamber by a carrier. The projectile is separated from thecarrier prior to firing.

A projectile-carrier assembly constructed in accordance with oneembodiment of the present invention is illustrated generally by thereference numeral 49 in FIG. 2. The projectile-carrier assembly 49includes a projectile 51 and a carrier 53.

The projectile 51 may have a reentry body configuration (as illustrated)with a narrow angle cone. The reentry body shape is aerodynamicallystabilized and has a low drag coefficient as shown by the chart of FIG.17. The projectile can also be a conventional spin stabilizedconfiguration.

The projectile 51 includes in bore stabilizing fins 55, a projectileseal 57, propellant flow grooves 59 and recesses or grooves 61 forattachment to the carrier 53.

The seal 57 also serves to retain the projectile in the barrel after theprojectile is loaded.

The carrier 53 has a relatively short axial length so as to contributelittle additional length to the overall projectile-carrier assembly. Thecarrier has a number of forwardly extending fingers or clips 63, andeach finger or clip 63 has a radially inwardly extending dimple orprojection 65 which seats in a groove 61 of the projectile.

When the carrier projectile assembly is placed in the bore, liquidpropellant is pumped through the propellant flow groove 59 and betweenthe back face 67 of the projectile and the inner face 69 of the carrierto pump or force the carrier 53 backwards to the rear end of the firingchamber of the receiver assembly in a manner which will be described indetail below with reference to FIGS. 1145. The resilient fingers 63 flexto permit the dimple 65 to release from the groove 61 during thisseparation operation.

In the event of a misfire the carrier 53 can be moved forward and can bereconnected with the projectile 51 to extract the projectile from thefiring chamber in a manner also to be described in greater detail below.

The carrier 53 includes a carrier seal 71.

The carrier also includes an alignment flat 73, best shown in FIG. 3.The alignment flat 73 coacts with a corresponding flat on the bolt toalign the projectilecarrier assembly in a manner to be described below.

The flat 73 maintains orientation of the carrier relative to theprojectile during the cycle, thus insuring that the dimples willproperly reengage the projectile in the event it must be removed fromthe bore in the event of malfunction.

The carrier 53 also includes an extraction lip 75. This extraction lip75 is engaged by a part on the bolt after the projectile has been fired.

The magazine 47 (as shown in FIGS. 7, 8, 9, 22 and 23) carries both thepropellant and the projectilecarrier assemblies. The propellant supplyis carried in a flexible tank or reservoir 79 within the magazinehousing. As best shown in FIGS. 22 and 23 the flexible tank 79 may haveaccordion type pleating and can be operated by a tape drive mechanism181 actuated by the bolt to lift the bottom of the tank 79 on each cycleof operation to pump propellant into the weapon.

The magazine shown in FIG. 7 includes expansion tanks 81 connected tothe main tank 79 by conduits 83.

As best shown in FIG. 9 the propellant supply part of the magazineincludes a spring loaded valve element 85 which seats in a valve seat 87when the magazine is not associated with the weapon. When the magazineis connected to the weapon, downwardly extending tube 89, as shown inFIG. 9, pushes the valve element 85 downwardly to establish fluidcommunication through a slot 91 in the sidewall of the tube 89.

The projectile-carrier assemblies are fed upwardly through a pair ofchannels 93 and into a common channel 95 and then into the receiverassembly of the weapon by the same bolt actuated elevator mechanism usedto lift the bottom wall of the propellant supply tank or reservoir 79.

A specific description of the lift mechanism for the magazine is setforth below with reference to FIGS. 22-24.

A strippable top 97 retains the projectiles in place until the magazineis loaded into the weapon.

A number of liquid propellants have been found satisfactory for theweapon of the present invention. They include but are not limited tomono propellants such as hydrazine nitrate composed of 35% N H NO 5% H 0and 60% N H Monomethyl l-lydrazine Nitrate 90%; Ethyl Propyl Nitrate60/40; Otto Fuel II.

A metal partition in the magazine serves to positively isolate theprimers in the projectile-carrier assembly from the propellant in thetank 79 to preclude inadvertent ignition. A suitable strap transfermechanism can be associated with the elevator strap 101, as shown inFIG. 24.

The receiver assembly 45, as shown in FIG. 9, has a two-part boltassembly. The bolt assembly includes an outer bolt 103 and an inner bolt105.

The outer bolt is reciprocal within a bore 107 in the receiver assembly45 and barrel 43.

The inner bolt 105 is reciprocable within a bore 109 in the outer bolt.

The tube 89 connecting the propellant supply in the magazine alsoconnects a tube or conduit 111 in the receiver assembly through apropellant control valve 113. The forward end of the tube 111 slideswithin a bore 114 in the outer bolt in trombone fashion during thereciprocation of the outer bolt 103.

A seal 110 seals between the tube 111 and the bore 1 13.

The forward end of the conduit 116 connects to the combustion chamber115 through a spring biased one way ball check valve 117 in the forwardface of the outer bolt 103.

A seal 119 is carried at the forward end of the outer bolt to sealagainst the wall 107 of the combustion chamber 115.

The forward end of the inner bolt 105 includes extractor clip 121 whichis resiliently biased by a spring 123. The forward ends of the resilientarms of the clip 121 clip over the extraction lip 75 of the carrier toremove the carrier from the bore 109 after firing.

An off center ejector pin 125 in the inner bolt (See FIG. kicks thecarrier out through an ejection slot 127 in the outer bolt and in thereceiver assembly 45.

A firing pin 129 is reciprocable within a bore 131 in the inner bolt toignite the propellant igniter 77 in the carrier.

A bolt lock 133, see FIG. 10, is pivoted about a pivot 135 and is springbiased towards the position illustrated in FIG. 10 by a spring 137 toplace the forward face of the bolt lock in locking engagement with therear face 139 of both the outer bolt 103 and the inner bolt 105. A cam139 moves forward and engages a corresponding cam surface 141 on thebolt lock 133 to pivot the bolt lock against the force of the spring 137to release the bolt at the end of the firing cycle.

The operation of the weapon thus far described is illustrated in FIGS.11-16 which illustrate respectively projectile transfer, projectileramming, propellant loading, combustion, and the carrier ejection.

The automatic firing cycle is initiated with the bolt in the openposition after the firing of a burst. This eliminates cook-off of around in the hot breech. Propellant isolation is effected by supplyingthe propellant through the bolt. This allows insertion of a thermalbarrier between the barrel and receiver group, effectively isolating thehot barrel from those components in direct contact with liquidpropellant.

There is little likelihood of dynamic cook-off of propellant duringloading. Static cook-off, however, can be a problem, as it is withcaseless solid propellant ammunition.

It is therefore an important feature of the present invention that thepropellant supply is isolated from those hot surfaces which might effectignition of a chambered round or ignition in the propellant supply.

When released by the trigger operated sear, the bolt pcks up a carrierand projectile from the clip and inserts the assembly into the boltbore. The bolt-operated elevator mechanism of the magazine, describedabove, effects this action by lifting the entire string ofprojectile-carrier assembly described above.

The flat 73 on the carrier extractor ram aligns the carrier.

The bolt is then driven forward, as illustrated in FIG. 12, by theoperating mechanism until the projectile 51 engages the bore opening ofthe weapon at the forward end of the combustion chamber 115.

The propellant valve 113 is then opened, as illustrated in FIG. 13. Thisallows propellant supply pressure to 1) seat the projectile, 2) separatethe projectile carrier from the projectile within the bolt, and 3) fillthe combustion chamber with propellant as the bolt is moved rearward, asillustrated in FIG. 13, to its firing position.

During this phase of operation the propellantflows past the one-way ballcheck valve 117 and enters the carrier through the opening between thefingers or clips 63 in the carrier wall. The propellant flows throughthe propellant flow grooves 59 in the projectile 51 and acts on the rearface 67 of the projectile 51 and the forward inner face 69 of thecarrier.

When the firing chamber 115 is filled, the bolt is locked in its rearposition by the lock 133 (See FIG.

The firing pin 129 is released, and the firing pin strikes thepercussion primer 77, igniting the liquid propellant charge in thecombustion chamber 115.

After projectile exit, the bolt is opened, the spent projectile carrieris ejected as illustrated in FIG. 15,

and a subsequent cycle is initiated as long as the trigger is depressed.

The weapon may also be operated in a semiautomatic mode if a burst hasnot been fired recently. In the semi-automatic mode the man firing thegun hand operates an operating handle to fill the firing chamber 115with propellant and to position the parts in their relative positionsasassumed at the end of propellant loading as illustrated in FIG. 13. Inthis case the weapon is in effect cocked and ready to fire when thetrigger is pulled and the firing pin is released to engage the igniter77 as illustrated in FIG. 14. The weapon can continue to operate in thesemi-automatic mode as long as the chamber 115 does not become hotenough to allow static cook-off.

A thermostatic element can be included in the weapon to overridesemi-automatic operation when the chamber housing is too hot to allowsemi-automatic operation from a filled chamber.

As illustrated in FIG. 17 the drag coefficient for the reentry bodyprojectile is quite low, especially in comparison to projectiles havingconfigurations which are presently being used. The small bore liquidpropellant gun of the present invention permits the use of this reentrybody configuration by providing the requisite high velocity foraerodynamic stabilization. The weapon of the present invention canproduce high velocity (as a practical matter) because the liquidpropellant combustion does not heat the barrel as much as solidpropellant combustion. The cooler burning characteristics of the liquidpropellant are graphically illustrated in FIG. 16. This figure shows theenvelope of peak bore surface temperatures during eight round bursts ofliquid and solid propellant ammunition.

A weapon constructed in accordance with another embodiment of theinvention is illustrated in FIGS. 18, 19 and 20.

The weapon shown in FIGS. 18 and 19 embodies two important features.

A reciprocating combustion chamber housing slides over the rear end ofthe barrel and replaces the conventional bolt mechanism.

The magazine is a completely self-contained magazine which incorporatesa propellant pump, a chamber high pressure inlet valve and a clip ofprojectile-carrier assemblies.

When the reciprocable combustion chamber housing of the embodiment ofthe weapon shown in FIG. 18 is fully forward, the combustion chamber iscompletely eliminated. As the housing moves to the rear, the combustioncavity is fomied in a manner which eliminates ullage.

This embodiment of the present invention achieves a low length todiameter ratio for the combustion chamber. This minimizes receiverlength and improves chamber wall cooling due to the liquid annulusremaining at the time of initiation.

This reciprocating housing construction permits the use of a static lockfor the combustion chamber.

Combustion loads are not carried through a receiver but are carriedthrough the static members linking the barrel to the chamber.

It provides convenient means of thermal isolation for the chamber.

It permits ready increase of velocity level by using a longer chamberand stroke.

Propellant passages in the receiver mechanism are eliminated whichsimplifies the mechanism, eliminates voids and eliminates propellantfilled passages which could transmit flame from the combustion chamberto the propellant supply in the magazine.

As illustrated in FIG. 18 a combustion chamber housing 161 slides backand forth on the outer surface 163 of the end of the barrel 43.

The housing 161 is shown in its rearward most position in FIG. 18 readyfor firing. The combustion chamber housing 161 and the bolt are held inthis position by a static or stationary lock 165. The lock 165 abuts theback face of the housing 161. The lock 165 includes an inner recess 167hwich engages a radially projecting tang 169 of the bolt. The tank 169is rotated into locking engagement with the recessed surface 167 of thelock.

A seal 171 at the forward end of the housing 161 seals between thehousing 161 and the barrel surface 163.

Liquid propellant is admitted to the combustion chamber 151 through aport 173 in the housing 161.

A valve element 175 controls the admission of liquid propellant throughthe port 173. The valve element 175 is reciprocable within a bore 177 inthe housing 161, and a vent 179 vents the forward end of the bore 177.

As described below, a strap transfer mechanism 181 is operated bymovement of the bolt to lift a toothed strap 101 to elevate the bottomwall of the propellant tank 79 and the bottom wall of the clip for theprojectiles on each cycle of operation.

FIGS. 22 and 23 illustrate schematically operation of the strap transfermechanism 181. Two straps 101 are provided, one to raise the projectilesand the other to compress the propellant supply bellows.

The strap transfer drive tang 184 engages a slot in the bolt whichcauses reciprocation of drive tang 184. During rearward motion of thetang its teeth engage corresponding teeth on plastic strap 101 causingit to be transported to the rear and at the same time rotating take upreel 188. When the bolt moves forward, holding clutch 186 preventsrelaxation of the tension on strap 101. Excess tension in the strap isprevented by slipping action between the drive teeth of tang 184 andstrap 101 which is controlled by the spring load on holding clutch 186.

FIG. 19 illustrates the manner in which the projectile-carrierassemblies are fed into position in the front of the bolt.

A pair of resilient clips at the upper end of the passage 95 holds theuppermost projectile in position until the forward movement of the boltpushes the projectile carrier into the combustion chamber.

A tang or cam follower 183 on the bolt engages a groove or cam path tocontrol rotation of the bolt during reciprocating movement asillustrated in FIG. 20.

As noted above, the fiow of propellant to the combustion chamber 51 isunder the control of a valve element 175. This valve element 175 is apart of a pumping assembly which is indicated generally by the referencenumeral 191 and which is an integral part of the magazine 47.

The pumping assembly 191 includes three operating elements. Theseelements are a reciprocable outer housing 193, a piston 195 and thevalve element 175.

The piston 195 slides within a bore 197 within the outer housing 193,and is connected to a piston rod 199 which extends outwardly through asealed opening in the rearward end of the outer housing 193.

The valve element 175 is connected to a rod 201 which extends through aseal in the piston 195 and which is reciprocable within a bore 203 inthe rod 199.

The outer housing 193, the rod 199 and the rod 201 each have an upwardlyextending lip which is releasably engaged by an operating element 205,207 and 209 respectively of the weapon.

The rear face of the valve element 175 has a seal element 211 whichengages a forward annular face of the outer housing 193 in sealingrelationship in the position illustrated in FIG. 18.

The valve element 175 also includes sealing members 213 and 215. Thesesealing elements are high pressure seals which prevent any flow out thecombustion chamber 151 during combustion.

Propellant is drawn into the chamber formed in the bore 197 in front ofthe piston 195, during one phase of operation of the weapon, through aconduit 217 in the outer housing 193 and past a spring biased one-wayball check valve 219. The conduit 217 has an extension 217A whichcompensates for reciprocation of the conduit 217 within the reservoir 79to prevent an unequal displacement of volume during reciprocation.

As in the embodiment of the invention described with reference to FIGS.9-15, the embodiment illustrated in FIGS. 18 and 19 can operate in twomodes the automatic mode for firing bursts and semiautomatic mode.

The automatic mode is started with the bolt 105 fully retracted behindthe projectile assembly. The reciprocating combustion chamber housing161 is fully rearward with the rear face 166 in abutment with the lockAt this point the strap 101 has operated to lift the bottom of themagazine to position a projectile-carrier assembly in front of the bolt.

The bolt 105 is then moved forward. This transfers theprojectile-carrier assembly forward until the projectile 51 is seated inthe barrel and the elastomer seal 57 engages the inside of the barrel toform a liquid seal.

Locking and unlocking of the bolt is controlled by the action of the campath 185 on the bolt cam follower 183. Forward and backward movement ofthe cam slide 160 is controlled by the gas piston push rod 162. Thiscamming action rotates the bolt prior to forward or backward movement ofthe bolt assembly. A manual override 164 is provided to permit handoperation of the bolt in event of misfire.

In a typical firing cycle the gas piston push rod 162 is driven to therear by combustion gasses as the projectile passes by a gas port nearthe muzzle. Rearward motion of the push rod 162 and cam slide 160 rotatethe bolt cam follower 183 counterclockwise (viewed from the rear) todisengage the bolt tang 169 from the bolt lock inner recess 167 allowingthe bolt to move to the rear, extracting and ejecting the spentprojectile carrier. At its rearmost position the bolt picks up a newprojectile and carrier assembly and during forward motion loads thisassembly into the combustion chamber housing. Continued forward motionof the cam slide 160 rotates the bolt clockwise and carries thecombustion chamber housing 161 forward until barrel surface 44 is inabutment with housing surface 160 at which time the pumping cycle isinitiated as described above.

FIGS. 21A-D show another embodiment ofa projectile-carrier assemblyincorporating a coacting tang and slot construction for positiveextraction in the event of misfire. The propellantflow ports and groovesare omitted in FIGS. 21A-D for clarity of illustration but are the sameas in the embodiment shown in FIGS. 2-5.

As best shown in FIG. 213, the carrier has a tang the end of a finger63.

As best shown in FIG. 21D the projectile has a slot 60 with a recess 62.

In normal operation the tang 70 does not engage the recess 62. Thespring action of the fingers 63 hold the projectile in place duringloading.

If there is a misfire, the normal counterclockwise rotation of the boltcauses the tang 70 to be engaged in the recess 62 when the carrier isreconnected to the unfired projectile.

The tang 70 is never engaged in the recess 62 except in the event of amisfire. The normal loading and locking movement of the bolt isclockwise.

As the bolt is moved forward, the outer housing 193 of the pumpingassembly 191 is also moved forward with the valve element 175. Thispermits propellant to flow through the passage 217 and pass the checkvalve 219 into a chamber which is formed between the front face of thepiston 195 and the rear inner face of the forward part of the valve ofthe outer housing 193. j

The forward movement of the outer housing 193 and the valve element 175is then discontinued while the forward movement of the valve element 175is continued. The valve element 175 jogs forward enough to uncover theport 173. Propellant can then flow from the chamber in front of thepiston 195 through the bore 231 in the center part of the forward end ofthe outer housing 193 and through the port 173 and into the combustionchamber 151.

The outer housing 193 is then moved to the rear by the actuatingmechanism 205 while the piston 195 is held stationary. This pumps thepropellant into the combustion chamber 151. This in turn moves thereciprocating combustion chamber housing 161 to the rear and separatesthe carrier 53 from the projectile 51.

When the rearward movement of the pump outer housing 193 and thecombustion chamber housing 161 has been completed, and the housing 161is in abutment with the stationary lock 165, actuating element 209 thenpulls valve element 175 rearward to the position illustrated in FIG. 18in which the high pressure seals 213 and 215 seal off any fluid flowthrough the port 173.

The bolt is moved to the rear with the rearward movement of the housing161.

At this point the weapon is ready for firing, and firing is accomplishedby the hammer striking the firing pin 129 to force the forward end ofthe firing pin into engagement with the back face of the carrier 53 toignit the igniter 77.

A conventional gas operated linkage connected to the bolt gives the bolta kick to the rear when the projectile passes the gas operator.

An off center ejector pin in the bolt, like the pin shown in FIG. 15tumbles the spent carrier out through an ejection slot.

1n the event of a misfire the valve element is moved forward to uncoverthe port 173, and a manually actuated misfire mechanism pushes thehousing 161 forward to pump out the propellant from the combustionchamber 151.

The bolt 105 is rotated with respect to the carrier 58 to engage theextraction clips of the bolt in the slot of the carrier to produce apositive grip between the bolt and the carrier. The bolt is then pulledback to extract the carrier and the projectile 51, and the entirereengaged carrier and projectile assembly is ejected through theejection slot at the end of rearward movement of the bolt.

In the semi-automatic mode the parts are manually actuated for the firstshot to the relative positions illustrated in FIG. 18 so that the weaponis ready to fire when the trigger is pulled.

As described above, with reference to the first embodiment of thisinvention, a thermostatic element can be provided to override thesemi-automatic operating mechanism when the chamber housing is too hotto allow semi-automatic operation from a filled chamber.

To remove the magazine 47 from the weapon illustrated in FIG. 18, a cliprelease is actuated to move the outer housing 193, the piston 195 andthe valve element 175 to the rear and to release the magazine housingfrom the receiver 45.

1t is an important feature of the embodiment of the present inventionshown in FIG. 18 that propellant passages in the receiver mechanism areeliminated. The only free volume is the connection from the combustionchamber 151 to the bore 177 through the relatively small port 173.

The high pressure seals 213 and 215 are replaced each time a newmagazine is used.

The flat seal 211 provides positive propellant isolation, and there isalways an atmospheric vent after the high pressure seal 215 and beforegetting to the propellant in the reservoir 79.

While we have illustrated and described the preferred embodiments of ourinvention, it is to be understood that these are capable of variationand modification, and we therefore do not wish to be limited to theprecise details set forth, but desire to avail ourselves of such changesand alterations as fall within the purview of the following claims.

We claim:

1. A method of loading liquid propellant into a firing chamber of aliquid propellant gun to avoid ullage problems comprising placing theforward face of a firing chamber in line contact with the rear face ofthe firing chamber, loading a projectile carrier assembly in firingposition in the bore of the gun while the front and rear faces of thefiring chamber are maintained in line contact, then pumping liquidpropellant into the firing chamber to displace the rear face of thefiring chamber axially with respect to the front face of the firingchamber, separating the carrier from the projectile as liquid propellantis pumped into the firing chamber, retaining the projectile in theforward face of the firing chamber and retaining the carrier in the rearface of the firing chamber as these two faces are axially separated, andthen igniting the liquid propellant in the firing chamber to fire theprojectile out the barrel of the gun.

2. A method as defined in claim 1 including pumping the liquidpropellant out of the firing chamber in the event ofa misfire, movingthe rear face of the combustion chamber into line contact with the frontface of the combustion chamber as the liquid propellant is pumped out ofthe firing chamber, reconnecting the carrier to the projectile as thefaces of the combustion chamber are reengaged in line contact, and thenextracting the projectile-carrier assembly from the gun.

3. A method as defined in claim 1 including locating the mechanism forpumping the liquid propellant into the firing chamber in structureassociated with the rear face of the firing chamber and maintaining themechanism for pumping the liquid propellant spaced from the firingchamber housing and from the barrel of the gun after the firing chamberhousing and the barrel have been heated to high temperatures by thefiring of a burst to thereby provide thermal isolation of the propellantfrom the hot barrel and the housing.

4. A method as defined in claim 1 wherein the rear face of thecombustion chamber is part of a reciprocating combustion chamberhousing.

5. A method as defined in claim 1 wherein the rear face of thecombustion chamber is a part of the bolt assembly.

6. A liquid propellant gun of the kind in which a projectile is loadedin the gun and liquid propellant is pumped into the combustion chamberbehind the projectile and is ignited to fire the projectile from thegun,

said gun comprising a combustion chamber having a front face and a rearface, I said front face having an opening for the projectile, said rearface being shaped complementary to the front face to engage the frontface in line contact across the full surface of the front face exceptfor the area of said opening,

moving means for moving one face relative to the other face into saidline contact with the other face and for moving the one face away fromthe other face and into firing position,

projectile loading means coordinated with said moving means for loadinga projectile in the opening in the front face while the rear face isengaged in said line contact with the front face across said fullsurface of the front face,

pumping means for pumping a liquid propellant into the combustionchamber,

and propellant control valve means effective to admit the pumped liquidpropellant into the combustion chamber at the start of movement of theone face away from the other face and to continue to admit said liquidpropellant continuously and in coordination with the movement of theother face by said moving means to said firing position to thereby fillthe entire chamber volume with liquid propellant simultaneously with theformation of the chamber and prevent ullage in the combustion chamber.

7. A gun as defined in claim 6 wherein the projectile has an elastomerseal and projectile holder extending circumferentially around theprojectile and engageable in fluid sealing and projectile retainingrelationship with the opening in the front face of the combustionchamber.

8. A gun as defined in claim 6 wherein the diameter of the combustionchamber is considerably larger than the diameter of the projectile toprovide large propellant-to-projectile mass ratios for high muzzlevelocities and small combustion chamber length-to-diameter ratios foracceptable interior ballistics.

9. A gun as defined in claim 6 including a magazine containing a clip ofprojectile-carrier assemblies and a tank of liquid propellant, andwherein the pumping means include a movable piston and high pressureseals in the magazine structure.

10. A liquid propellant gun of the kind in which a projectile is loadedin the gun and liquid propellant is pumped into the combustion chamberbehind the projectile and is ignited to fire the projectile from thegun,

said gun comprising, a combustion chamber having a forward face and arear face,

said front face having an opening for the projectile,

moving means for moving the rear face forward into line contact with thefront face and for moving the rear face backward away from the frontface and into firing position, projectile loading means for loading aprojectile in the opening in the front face while the rear face isengaged in line contact with the front face,

pumping means for pumping a liquid propellant into the combustionchamber as the combustion chamber is formed by rearward movement of therear face whereby ullage in the combustion chamber is avoided, andwherein the projectile loading means include a projectile-carrierassembly having a carrier detachably connected to the projectile fortransporting the projectile and wherein the rear face of the combustionchamber has an opening and the carrier is engaged in fluid sealingcontact in said rear face opening and is disconnected from theprojectile as liquid propellant is pumped into the combustion chamberduring rearward movement of the rear face.

11. A gun as defined in claim wherein the carrier and projectile havecoacting ports and grooves in the sides of the carrier and projectilefor permitting liquid propellant to enter between the back face of theprojectile and a forward inner face of the carrier to separate thecarrier from projectile.

12. A gun as defined in claim 10 wherein the carrier has a percussiveigniter for igniting the liquid propel- Iant.

13. A gun as defined in claim 10 wherein the carrier has a rear carrierrim and a flat formed on the carrier rim for orienting the projectileand carrier assembly with respect to other operating mechanism of thegun.

14. A gun as defined in claim 13 wherein the projectile and carrier havecoacting positive locking means which can be engaged to extract theprojectile-carrier assembly in the event of a misfire and wherein theflat on the carrier rim permits rotation of the carrier relative to theprojectile to actuate the positive locking means.

15. A liquid propellant gun of the kind in which a projectile is loadedin the gun and liquid propellant is pumped into the combustion chamberbehind the projectile and is ignited to fire the projectile from thegun,

said gun comprising a combustion chamber having a front face and a rearface,

said front face having an opening for the projectile,

said rear face being shaped complementary to the front face to engagethe front face in line contact across the full surface of the front faceexcept for the area of said opening,

moving means for moving one face relative to the other face into saidline contact with the other face and for moving the one face away fromthe other face and into firing position,

projectile loading means for loading a projectile in the opening in thefront face while the rear face is engaged in said line contact with thefront face, and

pumping means for pumping a liquid propellant into the combustionchamber as the combustion chamber is formed by movement of the facesapart from each other to fill the entire chamber volume with liquidpropellant simultaneously with the formation of the chamber wherebyullage in the combustion chamber is avoided and wherein the front faceof the combustion chamber is formed on the end of the barrel of the gun,said gun includes a reciprocating combustion chamber housing, thehousing includes a forwardly extending portion having one inside surfaceslidable on and sealingly engaged with the outside surface of thebarrel, and another inside surface of the housing forms said rear faceof the combustion chamber.

16. A liquid propellant gun of the kind in which a projectile is loadedin the gun and liquid propellant is pumped into the combustion chamberbehind the projectile and is ignited to fire the projectile from thegun,

said gun comprising a combustion chamber having a front face and a rearface,

said front face having an opening for the projectile,

said rear face being shaped complementary to the front face to engagethe front face in line contact across the full surface of the front faceexcept for the area of said opening,

moving means for moving one face relative to the other face into saidline contact with the other face and for moving the one face away fromthe other face and into firing position,

projectile loading means for loading a projectile in the opening in thefront face while the rear face is engaged in said line contact with thefront face, and

pumping means for pumping a liquid propellant into the combustionchamber as the combustion chamber is formed by movement of the facesapart from each other to fill the entire chamber volume with liquidpropellant simultaneously with the formation of the chamber wherebyullage in the combustion chamber is avoided and including a boltassembly and wherein the rear face is a part of the bolt assembly andsaid bolt assembly includes a passageway extending through said rearface and interconnecting the pumping means and the chamber.

17. A liquid propellant gun of the kind in which a projectile is loadedin the gun and liquid propellant is pumped into the combustion chamberbehind the projectile and is ignited to fire the projectile from thegun,

said gun comprising, a combustion chamber having a forward face and arear face,

said front face having an opening for the projectile,

moving means for moving the rear face forward into line contact with thefront face and for moving the rear face backward away from the frontface and into firing position,

projectile loading means for loading a projectile in the opening in thefront face while the rear face is engaged in line contact with the frontface,

pumping means for pumping a liquid propellant into the combustionchamber as the combustion chamber is formed by rearward movement of therear face whereby ullage in the combustion chamber is avoided,

a magazine containing a clip of projectile-carrier assemblies, a tank ofliquid propellant, and the pumping means,

a rearwardly extending part of the barrel assembly which includes thefront face of the combustion chamber, a reciprocating combustion chamberhousing which includes the rear face of the combustion chamber, saidhousing having a forwardly extending part which has an inner surfaceslidable on and sealingly engaged with an outer surface of therearwardly extending part of the barrel, port means in the housing, anda valve element of the pumping means of the magazine associated with theport means of the housing to control the flow of liquid propellant fromthe magazine to the combustion chamber through the port means of thehousing.

18. A gun as defined in claim 17 wherein the valve element has highpressure seals on the valve element for preventing loss of fluidpressure out of the combustion chamber during firing whereby the highpressure seals are replaced each time a new magazine is connected to thegun.

19. A liquid propellant gun constructed to avoid ullagc problems in theloading of liquid propellant in the firing chamber, said gun comprising,actuator means for placing the forward face of a firing chamber in linecontact with the rear face of the firing chamber, loading means forloading a projectile carrier assembly in firing position in the bore ofthe gun while the front and rear faces of the firing chamber aremaintained in line contact, pumping means for pumping liquid propellantinto the firing chamber to displace one face of the firing chamberaxially with respect to the other face of the firing chamber, separatingmeans for separating the carrier from the projectile as liquidpropellant is pumped into the firing chamber, retaining means forretaining the projectile in the forward face of the firing chamber andfor retaining the carrier in the rear face of the firing chamber asthese two faces are axially separated, and igniter means for ignitingthe liquid propellant in the firing chamber to fire the projectile outthe barrel of the gun.

' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. q'803 975 Dated April 16. 1914 I fl Lester C. Elmore and Thomas M.Broxholm It is certified that error appears in the aboveidentifiedpatent and that said Letters Patent are hereby corrected as shown below:

Page 1, after title, insert --Some of the inventions herein describedwere made (first reduced to practice) in the course of or under acontract with ARPA.- Column 5, line 33, after "partition" insert -l0l--.Column 6, line 35, "pcks" should read --picks--. Column 8, line 14,"hwich" should read a --which--; line 15, "tank" should read --tang--.

. Signed and sealed this 29th day of October 1974.

(SEAL) Attest McCOY-M. GIBSONJR. c. MARSHALL DANN Attesting OfficerCommissioner of Patents FORM 9 5 USCOMM-DC 60376-P69 11.5. GOVERNMENTPRINTING OFFICE ID! 0-5.5-35,

' UNITED STATES PATENT OFFICE EERTIFICATE 0F CORRECTION PatentN L803975Dated Aorilvl6. 1974 I Lester C. Elmore and Thomas M. Broxholm It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Page 1 after title, insert --Some of the inventions herein describedwere made (first reduced to practice) in the course of or under acontract with ARPA.- I Column 5, line 33, after "partition" insert-l0l--. Column 6, line 35, "pcks" should read --picks. Column 8, line14, "hwich" should read --which--; line 15, "tank" should read --tang--.

v Signed and sealed this 29th day of October 1974.

(SEAL) Attest MCCOY GIBSON JR. c. MARSHALL DANN Attesting OfficerCommissioner of Patents

1. A method of loading liquid propellant into a firing chamber of aliquid propellant gun to avoid ullage problems comprising placing theforward face of a firing chamber in line contact with the rear face ofthe firing chamber, loading a projectile carrier assembly in firingposition in the bore of the gun while the front and rear faces of thefiring chamber are maintained in line contact, then pumping liquidpropellant into the firing chamber to displace the rear face of thefiring chamber axially with respect to the front face of the firingchamber, separating the carrier from the projectile as liquid propellantis pumped into the firing chamber, retaining the projectile in theforward face of the firing chamber and retaining the carrier in the rearface of the firing chamber as these two faces are axially separated, andthen igniting the liquid propellant in the firing chamber to fire theprojectile out the barrel of the gun.
 2. A method as defined in claim 1including pumping the liquid propellant out of the firing chamber in theevent of a misfire, moving the rear face of the combustion chamber intoline contact with the front face of the combustion chamber as the liquidpropellant is pumped out of the firing chamber, reconnecting the carrierto the projectile as the faces of the combustion chamber are reengagedin line contact, and then extracting the projectile-carrier assemblyfrom the gun.
 3. A method as defined in claim 1 including locating themechanism for pumping the liquid propellant into the firing chamber instructure associated with the rear face of the firing chamber andmaintaining the mechanism for pumping the liquid propellant spaced fromthe firing chamber housing and from the barrel of the gun after thefiring chamber housing and the barrel have been heated to hightemperatures by the firing of a burst to thereby provide thermalisolation of the propellant from the hot barrel and the housing.
 4. Amethod as defined in claim 1 wherein the rear face of the combustionchamber is part of a reciprocating combustion chamber housing.
 5. Amethod as defined in claim 1 wherein the rear face of the combustionchamber is a part of the bolt assembly.
 6. A liquid propellant gun ofthe kind in which a projectile is loaded in the gun and liquidpropellant is pumped into the combustion chamber behind the projectileand is ignited to fire the projectile from the gun, said gun comprisinga combustion chamber having a front face and a rear face, said frontface having an opening for the projectile, said rear face being shapedcomplementary to the front face to engage the front face in line contactacross the full surface of the front face except for the area of saidopening, moving means for moving one face relative to the other faceinto said line contact with the other face and for moving the one faceaway from the other face and into firing position, projectile loadingmeans coordinated with said moving means for loading a projectile in theopening in the front face while the rear face is engaged in said linecontact with the front face across said full surface of the front face,pumping means for pumping a liquid propellant into the combustionchamber, and propellant control valve means effective to admit thepumped liquid propellant into the combustion chamber at the start ofmovement of the one face away from the other face and to continue toadmit said liquid propellant continuously and in coordination with themovement of the other face by said moving means to said firing positionto thereby fill the entire chamber volume with liquid pRopellantsimultaneously with the formation of the chamber and prevent ullage inthe combustion chamber.
 7. A gun as defined in claim 6 wherein theprojectile has an elastomer seal and projectile holder extendingcircumferentially around the projectile and engageable in fluid sealingand projectile retaining relationship with the opening in the front faceof the combustion chamber.
 8. A gun as defined in claim 6 wherein thediameter of the combustion chamber is considerably larger than thediameter of the projectile to provide large propellant-to-projectilemass ratios for high muzzle velocities and small combustion chamberlength-to-diameter ratios for acceptable interior ballistics.
 9. A gunas defined in claim 6 including a magazine containing a clip ofprojectile-carrier assemblies and a tank of liquid propellant, andwherein the pumping means include a movable piston and high pressureseals in the magazine structure.
 10. A liquid propellant gun of the kindin which a projectile is loaded in the gun and liquid propellant ispumped into the combustion chamber behind the projectile and is ignitedto fire the projectile from the gun, said gun comprising, a combustionchamber having a forward face and a rear face, said front face having anopening for the projectile, moving means for moving the rear faceforward into line contact with the front face and for moving the rearface backward away from the front face and into firing position,projectile loading means for loading a projectile in the opening in thefront face while the rear face is engaged in line contact with the frontface, pumping means for pumping a liquid propellant into the combustionchamber as the combustion chamber is formed by rearward movement of therear face whereby ullage in the combustion chamber is avoided, andwherein the projectile loading means include a projectile-carrierassembly having a carrier detachably connected to the projectile fortransporting the projectile and wherein the rear face of the combustionchamber has an opening and the carrier is engaged in fluid sealingcontact in said rear face opening and is disconnected from theprojectile as liquid propellant is pumped into the combustion chamberduring rearward movement of the rear face.
 11. A gun as defined in claim10 wherein the carrier and projectile have coacting ports and grooves inthe sides of the carrier and projectile for permitting liquid propellantto enter between the back face of the projectile and a forward innerface of the carrier to separate the carrier from projectile.
 12. A gunas defined in claim 10 wherein the carrier has a percussive igniter forigniting the liquid propellant.
 13. A gun as defined in claim 10 whereinthe carrier has a rear carrier rim and a flat formed on the carrier rimfor orienting the projectile and carrier assembly with respect to otheroperating mechanism of the gun.
 14. A gun as defined in claim 13 whereinthe projectile and carrier have coacting positive locking means whichcan be engaged to extract the projectile-carrier assembly in the eventof a misfire and wherein the flat on the carrier rim permits rotation ofthe carrier relative to the projectile to actuate the positive lockingmeans.
 15. A liquid propellant gun of the kind in which a projectile isloaded in the gun and liquid propellant is pumped into the combustionchamber behind the projectile and is ignited to fire the projectile fromthe gun, said gun comprising a combustion chamber having a front faceand a rear face, said front face having an opening for the projectile,said rear face being shaped complementary to the front face to engagethe front face in line contact across the full surface of the front faceexcept for the area of said opening, moving means for moving one facerelative to the other face into said line contact with the other faceand for moving the one face away from the other face and into firingposition, projectile loadinG means for loading a projectile in theopening in the front face while the rear face is engaged in said linecontact with the front face, and pumping means for pumping a liquidpropellant into the combustion chamber as the combustion chamber isformed by movement of the faces apart from each other to fill the entirechamber volume with liquid propellant simultaneously with the formationof the chamber whereby ullage in the combustion chamber is avoided andwherein the front face of the combustion chamber is formed on the end ofthe barrel of the gun, said gun includes a reciprocating combustionchamber housing, the housing includes a forwardly extending portionhaving one inside surface slidable on and sealingly engaged with theoutside surface of the barrel, and another inside surface of the housingforms said rear face of the combustion chamber.
 16. A liquid propellantgun of the kind in which a projectile is loaded in the gun and liquidpropellant is pumped into the combustion chamber behind the projectileand is ignited to fire the projectile from the gun, said gun comprisinga combustion chamber having a front face and a rear face, said frontface having an opening for the projectile, said rear face being shapedcomplementary to the front face to engage the front face in line contactacross the full surface of the front face except for the area of saidopening, moving means for moving one face relative to the other faceinto said line contact with the other face and for moving the one faceaway from the other face and into firing position, projectile loadingmeans for loading a projectile in the opening in the front face whilethe rear face is engaged in said line contact with the front face, andpumping means for pumping a liquid propellant into the combustionchamber as the combustion chamber is formed by movement of the facesapart from each other to fill the entire chamber volume with liquidpropellant simultaneously with the formation of the chamber wherebyullage in the combustion chamber is avoided and including a boltassembly and wherein the rear face is a part of the bolt assembly andsaid bolt assembly includes a passageway extending through said rearface and interconnecting the pumping means and the chamber.
 17. A liquidpropellant gun of the kind in which a projectile is loaded in the gunand liquid propellant is pumped into the combustion chamber behind theprojectile and is ignited to fire the projectile from the gun, said guncomprising, a combustion chamber having a forward face and a rear face,said front face having an opening for the projectile, moving means formoving the rear face forward into line contact with the front face andfor moving the rear face backward away from the front face and intofiring position, projectile loading means for loading a projectile inthe opening in the front face while the rear face is engaged in linecontact with the front face, pumping means for pumping a liquidpropellant into the combustion chamber as the combustion chamber isformed by rearward movement of the rear face whereby ullage in thecombustion chamber is avoided, a magazine containing a clip ofprojectile-carrier assemblies, a tank of liquid propellant, and thepumping means, a rearwardly extending part of the barrel assembly whichincludes the front face of the combustion chamber, a reciprocatingcombustion chamber housing which includes the rear face of thecombustion chamber, said housing having a forwardly extending part whichhas an inner surface slidable on and sealingly engaged with an outersurface of the rearwardly extending part of the barrel, port means inthe housing, and a valve element of the pumping means of the magazineassociated with the port means of the housing to control the flow ofliquid propellant from the magazine to the combustion chamber throughthe port means of the housing.
 18. A gun as defined in claim 17 whereinthe valve element has high presSure seals on the valve element forpreventing loss of fluid pressure out of the combustion chamber duringfiring whereby the high pressure seals are replaced each time a newmagazine is connected to the gun.
 19. A liquid propellant gunconstructed to avoid ullage problems in the loading of liquid propellantin the firing chamber, said gun comprising, actuator means for placingthe forward face of a firing chamber in line contact with the rear faceof the firing chamber, loading means for loading a projectile carrierassembly in firing position in the bore of the gun while the front andrear faces of the firing chamber are maintained in line contact, pumpingmeans for pumping liquid propellant into the firing chamber to displaceone face of the firing chamber axially with respect to the other face ofthe firing chamber, separating means for separating the carrier from theprojectile as liquid propellant is pumped into the firing chamber,retaining means for retaining the projectile in the forward face of thefiring chamber and for retaining the carrier in the rear face of thefiring chamber as these two faces are axially separated, and ignitermeans for igniting the liquid propellant in the firing chamber to firethe projectile out the barrel of the gun.